This invention relates generally to self-propelled aerial work platforms and more particularly to an improved extensible boom therefor which has internally positioned hydraulic lines and electrical cables.
Self-propelled hydraulic boom lifts with elongate longitudinally extensible booms mounted thereon for controlled horizontal and vertical pivotal movement and for selective extension and contraction of the boom are old and well known in the art.
Extensible booms of the type under consideration have forward free ends and pivotally mounted rear ends. Such booms are generally made up of two or more elongate, telescopically engaged, tubular sections. The larger in cross-section or outer boom section commonly establishes the rear pivotally mounted end of the boom. The smallest in cross-ection or inner boom section establishes the front free end of the boom, with which work platforms or other work performing gear are related. The sections of the booms are (most commonly) driven longitudinally relative to each other by elongate, hydraulic cylinder and ram units arranged within and extending longitudinally of the boom sections. In those booms which include more than two sections, sheave and wire cable systems are connected with and between the sections which are driven by the cylinder and ram units and the sections which are not driven by those units, to effect desired relative axial shifting of all of the boom sections.
Boom lifts with extensible booms carrying work platforms at their forward free ends and which include manually operable control means at the platforms to enable workmen to effect desired operation of the booms, contain elongate, flexible hydraulic lines and electrical cables which extend from the platforms at the front ends of the booms to the rear ends of the booms to connect with related hydraulic and/or electric drive and control means provided to operate the booms and which are carried by the vehicles. In such boom lifts, the lines and cables must be sufficiently long to enable the booms to be extended to their maximum longitudinal extent. Accordingly, when the booms are not fully extended, the lines and cables are slack and extend loosely between the front and rear ends of the booms.
The aforesaid lines and cables have been difficult to handle and to protect against damage. Thus, when the subject lines and cables are arranged within their related boom structures, they interfere with other parts of the boom structures and are subject to being rapidly worn and otherwise damaged or destroyed. It has been learned that when such lines and cables are mounted on the exteriors of the boom structures, there is little that can be done to effectively protect them against damage by snow and ice and by engagement with trees and other like obstructions.
The prior art has made special efforts to provide means to effectively handle and protect the hydraulic lines and electrical cables which are associated with and which extend longitudinally of extensible booms. WHile some of those efforts have resulted in structures which provide improved handling and protection, those structures, for the most part, have their own shortcomings and present new problems which are often as serious and troublesome as are the problems they seek to reduce or eliminate.
With the foregoing limitations and deficiencies of known devices in mind, it is an object of the present invention to provide an elongate, longitudinally extensible boom structure having novel means within its interior for holding and protecting hydraulic lines and electrical cables extending from one end to the other of the boom structure as the sections thereof extend and contract.
Another object of our invention is to provide novel means for holding and protecting hydraulic lines and electrical cables within an extensible boom structure which is substantially unaffected by externally applied forces and external conditions such as snow and ice.
A further object of our invention is to provide novel means for holding and protecting hydraulic lines and electrical cables within an elongate boom comprised of telescopically engaged tubular boom sections, which includes an elongate articulated link conduit positioned within and extending longitudinally of the boom with opposite ends anchored to those boom sections which define the opposite ends of the boom and in and through which the lines and cables are laid and protected.
The foregoing and other objects and advantages of our invention will be apparent and fully understood from the following detailed description of one preferred form and embodiment of our invention, throughout which description reference is made to the accompanying drawings.